4.3.2 mysqld_safe — MySQL Server Startup Script

mysqld_safe is the recommended way to start a
mysqld server on Unix.
mysqld_safe adds some safety features such as
restarting the server when an error occurs and logging runtime
information to an error log. A description of error logging is
given later in this section.

mysqld_safe reads all options from the
[mysqld], [server], and
[mysqld_safe] sections in option files. For
example, if you specify a [mysqld] section
like this, mysqld_safe will find and use the
--log-error option:

[mysqld]
log-error=error.log

For backward compatibility, mysqld_safe also
reads [safe_mysqld] sections, but to be
current you should rename such sections to
[mysqld_safe].

Read this option file in addition to the usual option files.
If the file does not exist or is otherwise inaccessible, the
server will exit with an error.
file_name is interpreted relative
to the current directory if given as a relative path name
rather than a full path name. This must be the first option
on the command line if it is used.

Use only the given option file. If the file does not exist
or is otherwise inaccessible, the server will exit with an
error. file_name is interpreted
relative to the current directory if given as a relative
path name rather than a full path name. This must be the
first option on the command line if it is used.

The name of the library to use for memory allocation instead
of the system malloc() library. As of
MySQL 5.5.52, the option value must be one of the
directories /usr/lib,
/usr/lib64,
/usr/lib/i386-linux-gnu, or
/usr/lib/x86_64-linux-gnu. Prior to
MySQL 5.5.52, any library can be used by specifying its path
name, but there is a shortcut form to enable use of the
tcmalloc library that is shipped with
binary MySQL distributions for Linux in MySQL
5.5. It is possible that the shortcut form will
not work under certain configurations, in which case you
should specify a path name instead.

Note

As of MySQL 5.5.50, MySQL distributions no longer include
a tcmalloc library.

The --malloc-lib option
works by modifying the LD_PRELOAD
environment value to affect dynamic linking to enable the
loader to find the memory-allocation library when
mysqld runs:

If the option is not given, or is given without a value
(--malloc-lib=),
LD_PRELOAD is not modified and no
attempt is made to use tcmalloc.

If the option is given as
--malloc-lib=tcmalloc,
mysqld_safe looks for a
tcmalloc library in
/usr/lib and then in the MySQL
pkglibdir location (for example,
/usr/local/mysql/lib or whatever is
appropriate). If tmalloc is found,
its path name is added to the beginning of the
LD_PRELOAD value for
mysqld. If
tcmalloc is not found,
mysqld_safe aborts with an error.

The name of the server program (in the
ledir directory) that you want to start.
This option is needed if you use the MySQL binary
distribution but have the data directory outside of the
binary distribution. If mysqld_safe
cannot find the server, use the
--ledir option to
indicate the path name to the directory where the server is
located.

As of MySQL 5.5.52, this option is accepted only on the
command line, not in option files.

Do not read any option files. If program startup fails due
to reading unknown options from an option file,
--no-defaults can be
used to prevent them from being read. This must be the first
option on the command line if it is used.

For logging to syslog, messages from
mysqld_safe and mysqld
are written with identifiers of
mysqld_safe and
mysqld, respectively. To specify a suffix
for the identifiers, use
--syslog-tag=tag,
which modifies the identifiers to be
mysqld_safe-tag
and
mysqld-tag.

Run the mysqld server as the user having
the name user_name or the numeric
user ID user_id.
(“User” in this context refers to a system
login account, not a MySQL user listed in the grant tables.)

If you execute mysqld_safe with the
--defaults-file or
--defaults-extra-file option
to name an option file, the option must be the first one given
on the command line or the option file will not be used. For
example, this command will not use the named option file:

mysql> mysqld_safe --port=port_num --defaults-file=file_name

Instead, use the following command:

mysql> mysqld_safe --defaults-file=file_name --port=port_num

The mysqld_safe script is written so that it
normally can start a server that was installed from either a
source or a binary distribution of MySQL, even though these
types of distributions typically install the server in slightly
different locations. (See
Section 2.1.4, “Installation Layouts”.)
mysqld_safe expects one of the following
conditions to be true:

The server and databases can be found relative to the
working directory (the directory from which
mysqld_safe is invoked). For binary
distributions, mysqld_safe looks under
its working directory for bin and
data directories. For source
distributions, it looks for libexec and
var directories. This condition should
be met if you execute mysqld_safe from
your MySQL installation directory (for example,
/usr/local/mysql for a binary
distribution).

If the server and databases cannot be found relative to the
working directory, mysqld_safe attempts
to locate them by absolute path names. Typical locations are
/usr/local/libexec and
/usr/local/var. The actual locations
are determined from the values configured into the
distribution at the time it was built. They should be
correct if MySQL is installed in the location specified at
configuration time.

Because mysqld_safe tries to find the server
and databases relative to its own working directory, you can
install a binary distribution of MySQL anywhere, as long as you
run mysqld_safe from the MySQL installation
directory:

shell> cd mysql_installation_directory
shell> bin/mysqld_safe &

If mysqld_safe fails, even when invoked from
the MySQL installation directory, specify the
--ledir and
--datadir options to
indicate the directories in which the server and databases are
located on your system.

Beginning with MySQL 5.5.21, mysqld_safe
tries to use the sleep and
date system utilities to determine how many
times it has attempted to start this second, and—if these
are present and this is greater than 5 times—is forced to
wait 1 full second before starting again. This is intended to
prevent excessive CPU usage in the event of repeated failures.
(Bug #11761530, Bug #54035)

When mysqld_safe writes a message, notices go
to the logging destination (syslog or the
error log file) and stdout. Errors go to the
logging destination and stderr.

Normally, you should not edit the mysqld_safe
script. Instead, configure mysqld_safe by
using command-line options or options in the
[mysqld_safe] section of a
my.cnf option file. In rare cases, it might
be necessary to edit mysqld_safe to get it to
start the server properly. However, if you do this, your
modified version of mysqld_safe might be
overwritten if you upgrade MySQL in the future, so you should
make a copy of your edited version that you can reinstall.